Microscopically, the specimen consisted of normal cerebellar architecture that abruptly merged with widened folia exhibiting a disorganized cerebellar architectonic pattern in which Purkinje cell bodies were not recognized and the border between the molecular and granular layers could not be discerned. The internal granular cell layer was focally indistinct as such and was occupied by a population of large dysmorphic nerve cell bodies (Fig 3). The underlying white matter was atrophic and gliotic. Immunohistochemical staining for neurofilament protein confirmed the disoriented enlarged cells to be neurons (Fig 4), and also delineated the internal granular cell layer which merged both proximally and distally with well-formed cerebellar folia. An immunohistochemical stain for the MIB-1 (proliferation related) antigen revealed a labelling index < 1 %.
DIAGNOSIS AND DISCUSSION